Sheffield United have said they are "appalled" by the abuse being aimed at people who have criticised the club's decision to allow convicted rapist Ched Evans back to training.

It follows the Twitter abuse aimed at Olympic heptathlon champion and local hero Jessica Ennis-Hill, who said that to allow Evans back into the Blades squad would "completely contradict" her beliefs of being a role model to young people.

She was taunted with several sick tweets including one saying: "I hope he (Evans) rapes her."

This came after she asked for her name to removed from a stand at Sheffield United's Bramall Lane ground if the club takes back Evans, who was sentenced to five years for rape.

The club have pledged to work with South Yorkshire Police who are investigating the abuse. People who send this kind of abuse on social media or when chanting at grounds should not feel safe to make these personal attacks, the club said.

In a statement, the club said: "Sheffield United Football Club is appalled at the recent condemnation and abuse that has been levelled at both some of its more high-profile supporters and those who have no connections to the club but who have voiced their opinion on the matter.

"Regarding the personal tirade against individuals, the club will work with both South Yorkshire Police and any other supportive body to help identify the instigators. This will include abuse through social media messaging and chanting at grounds.

"Anyone who is found to be involved in such practice will be banned for life from Bramall Lane.

"Sheffield United will not accept the abuse that is being received by those who have voiced their opinion. They have felt it necessary and have been courageous enough to have made their statement and this should be respected."

Ennis-Hill, a United fan, had a stand at Bramall Lane named in her honour after she won gold at the London 2012 Olympics.

She issued her statement after the Blades' decision to accept a request from the Professional Footballers' Association to allow Evans to train at the club to help him regain his fitness.

She said: ''I believe being a role model to young people is a huge honour and those in positions of influence in communities should respect the role they play in young people's lives and set a good example.

''If Evans was to be re-signed by the club, it would completely contradict these beliefs.''

Campaigners against sexual violence have criticised the club's decision to allow Evans, 25, to train with the team.

TV presenter Charlie Webster, Sixties pop star Dave Berry and Sheffield businesswoman Lindsay Graham have all resigned as patrons of the club since Evans returned to training.

Wales international Evans was jailed in April 2012 for raping a 19-year-old woman in a hotel room in Rhyl, North Wales.

The striker denied raping the woman, saying the sex was consensual, but he was found guilty by a jury at Caernarfon Crown Court.

He was released from prison last month after serving half of the five-year sentence.

An appeal against his conviction was rejected by three judges at the Court of Appeal in 2012. His case is due to be looked at by the Criminal Cases Review Commission.

After his release, Evans put a video on his website protesting his innocence and vowing to clear his name.

South Yorkshire Police said on Friday: ''South Yorkshire Police can confirm they are investigating reports of abusive tweets. Officers are making efforts to contact the individual concerned, but have launched an investigation into the posts.''